1. Field of the Invention
This invention relates generally to the field of electrical connectors for semiconductor devices and, more particularly, to a semiconductor device having signal contacts and high current power contacts.
2. Description of the Related Art
Typically, electrical connectors having various configurations are employed for attaching integrated-circuit (IC) modules to printed-circuit (PC) boards. Such connectors provide versatility to computer platforms by allowing major components, such as microprocessors, to be easily removed and replaced with upgraded units. For example, one type of connector that is used for such a purpose is a zero-insertion-force (ZIF) sockets. A ZIF socket is useful in that very little downward force need be exerted as the device is being inserted or latched into the connector. Because no force is required, the potential for damage to the delicate signal pins of the component being inserted is reduced. The type of semiconductor device package that interfaces with a ZIF socket is referred to a pin grid array (PGA). A PGA package has a plurality of signal and power pins extending from the package, typically in a single plane.
One problem associated with a PGA package is the limited current carrying capacity of each pin. Accordingly, many pins are needed to provide sufficient power and ground supplies for the semiconductor device. As the complexity of current microprocessors increases, the power demands typically also increase. In addition, the number of pins needed for signals also increases (e.g., a 64-bit microprocessor requires more pins than a 32-bit microprocessor). Due to the current requirements of typical microprocessors, as many as ⅔ of the total number of pins may be dedicated for supplying power. This domination of the pins count constrains the number of pins remaining for signals. Additional pins equate to additional size and cost. The use of larger pins for power supply contacts to boost their current carrying capacity is impractical, as it increases the complexity of the assembly process.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
One aspect of the present invention is seen in a semiconductor device includes a casing, a semiconductor die supported by the casing, at least one contact pad disposed on a bottom surface of the semiconductor device, and a plurality of external contacts extending from the casing and being coupled to the semiconductor die.
Another aspect of the present invention is seen in a circuit assembly including a printed circuit board, a semiconductor device, and a socket. The semiconductor device includes a casing, a semiconductor die supported by the casing, at least one contact pad disposed on a bottom surface of the semiconductor device, and a plurality of external contacts extending from the casing and being coupled to the semiconductor die. The socket is coupled to the printed circuit board and adapted to receive the semiconductor device. The socket includes a first plurality of contacts adapted to interface with the external contacts of the semiconductor device and at least one base contact adapted to interface with the contact pad.